Clem 7 traffic estimates predict 50,000 car shortfall

Tony Moore

The Clem 7 tunnel will carry 54,000 fewer vehicles a day than its builders anticipate by 2026, according to traffic estimates provided as part of the building of the Northern Link tunnel.

If true, this would a mean shortfall in tolls collected of more than $200,000 a day, or $6 million a month.

In 2006, RiverCity Motorway won a 45-year concession to build and run the Clem 7, Brisbane's first road tunnel project, which will run from Bowen Hills to Woolloongabba and is due to open in mid-2010.

Its traffic estimates, provided by private toll company Maunsells, predict an average of 136,188 vehicles each day using the tunnel by 2026.

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However, traffic estimates completed by Sinclair Knight Merz and Connell Wagner in June as part of Brisbane City Council's Northern Link tunnel predict only 82,000 vehicles will use the Clem 7 tunnel by 2026.

That is 54,188 fewer vehicles on average each day.

Both companies say they have factored in the impact of the Northern Link tunnel, which runs from Toowong to Bowen Hills, and say it impossible to compare the estimates because "assumptions" for both are different.

But RiverCity Motorway's own financial statements point out the effects differing traffic projections could have on the $2.8 billion Clem 7 tunnel's financial base.

"If traffic assumptions over the entire concession period differed to estimates by +/-5% then the value in use would be impacted by +/- $99 million," its 2009 financial statement states.

Two Sydney tunnels have had troubled histories based on traffic projections that were never reached.

Sydney's Lane Cove tunnel, run by Connector Motorways, originally projected 100,000 vehicles a day by September 2007, but was struggling at 62,364 in February 2008.

By September this year 73,761 vehicles a day were using the tunnel plus the Military Road ramps.

A second Sydney tunnel, Sydney's Cross City Tunnel, was placed in the hands of receivers in April 2007 after projecting 90,000 vehicles a day, but carrying only 30,000.

Maunsell defended its traffic forecasts, saying it had sound forecasts on other tollway projects, such as Melbourne CityLink, and the M2 and WestLink M7 in Sydney.

A spokesman for Brisbane City Council described the Sinclair Knight Merz and Connell Wagner figures as "conservative", and the Maunsells figures as "aggressive".

Maunsells defended its 2006 modelling, describing it as "extremely detailed".

"It is important to note that these forecasts take into account future road network changes, including the opening of the Northern Link tunnel," a spokesman said.

"This forecast was prepared following extensive data collection, modelling of the transport network, consideration of potential network changes, existing and projected population and employment growth, planned urban development, assessment of people's willingness to pay tolls and other economic factors.

"It was a very in-depth study, focussing particularly on the Clem 7."

Brisbane City Council says the estimates by Sinclair Knight Merz and Connell Wagner for the Clem 7 tunnel project were completed in February 2005.

It includes estimates "with" and "without" Northern Link.

RiverCity Motorway refused to comment on the opposing figures when contacted by brisbantimes.com.au.

"RiverCity Motorway is not in a position to comment on the traffic forecasts prepared for the Northern Link EIS process and have no specific detail of the modelling undertaken," it said in a statement.

"Questions regarding Northern Link modelling should be referred to Brisbane City Council."

Brisbane City Council said its estimates for Clem 7 did include traffic projections, but was not as broad-based as the work completed by Maunsells.

The wide variation in the traffic modelling is apparent even earlier in the modelling.

By 2016 Maunsells estimates that 116,384 vehicles each day will use the Clem 7 tunnel, while the Sinclair Knight Merz Northern Link project team estimate 65,900 by 2014, growing at about 1350 vehicles a year.

6 comments so far

A growing number of people now realise what a monumental disaster these tunnels will mean for this city. This is 1950's American traffic policy.

What Campbell Newman won't say is that the contract to operate the tunnels contains a clause that Brisbane ratepayers must pay the operator any shortfall in toll revenues. We can expect our rates to skyrocket due to these wildly inaccurate traffic forecasts. And even then Newman's tunnels will not fix traffic congestion. We have voted an idiot in for Lord Mayor and will now pay the price for shortsighted policy.

Commenter

Hearsay of Brisbane

Date and time

November 03, 2009, 7:57AM

I don't know how these people work out their figures. 136,000 vehicles a day works out at around 6000 cars per hour. Or 100 cars per minute, (25 cars each lane), all day not just peak. The maximum safe capacity, (3 seconds distance between cars), is 20 cars per minute.
82,000 per day is just as unlikely. Outside of peak hours there will be little difference in time between using the existing "free" roads and the tunnel.
Who checked the figures? And we're stuck with the debt. Bet they introduce a toll on the ICB before the tunnel is 2 years old.

Commenter

TD

Location

Brisbane

Date and time

November 03, 2009, 8:35AM

This sounds like the Sydney cross city tunnel all over again.

Commenter

monkeymind

Date and time

November 03, 2009, 9:23AM

Have to say I don't mind the concept of the tunnels at all, what I don't like is the toll. I am one of those citizens who believe that I pay enough in my taxes, I shouldn't have to pay again to use roads that belong to me as a tax paying citizen. I don't use the gateway or the logan tollways out of principle. I will not use these new ones either. I also find it actually quicker to go around them, it's ten minutes quicker to go through the city and then southwards along the freeway than to use the gateway, a friend and I did the test again for the third time four weeks ago.

Commenter

Alex

Location

Brisbane

Date and time

November 03, 2009, 10:56AM

Hearsay: and I suppose inaccurate sledging is a better idea? The cars need to travel from North to South, and vice versa, that's how Brisbane's designed. This has nothing to do with inner-city traffic, no light rail can solve this problem. People need to DRIVE from one side of the city to the other. A tunnel is the only option unless you're interested in repossessing hundreds of houses and businesses above-ground. Blame the past council for not designing the city properly. Blame the population for their over-reliance on cars, but don't blame the guy that is trying to FIX the problem.

TD: Sure it's the recommended distance, but I've never seen traffic travelling through the ICB with three whole seconds between them. In fact, I've never seen traffic that far apart in peak hour - ever. ICB northbound at peak hour hits the RBH tunnel with 1 second between them. With your rudimentary logic that's 60 cars per minute per lane. 240 cars per minute for four lanes (Clem7). Maintain that for two hours peak hour each way and you have 57,600 cars in four hours. You now have 20 hrs left to pick up the rest. Even in off-peak, the tunnel will save you 10-15mins getting to the other side so I think there'll be enough takers to fill these estimates.

Commenter

ThatGuy

Date and time

November 03, 2009, 12:06PM

That Guy: Greenslopes to the Brekkie Creek via the ICB in either direction outside of peak hours takes less than 15 minutes. I do it regularly, so the tunnel won't save anytime at all. I serioulsy doubt if any of them will use the tunnel, day o
I realise my maths was a bit fundamental. However, you must also take into account the number of cars still using the M1/ICB, which will be free. Any increase in congestion in the tunnel will lead to more cars using the above ground option. And people who are paying for the toll out of their own pockets will put up with a bit of congestion, rather than use the cash from thie pay packets.
Your other assumption about cars needing to drive from north to south, also needs addressing. If we were to put the billions spent on the tunnel into addressing public transport options, eg, free travel before 7am, do we still need a tunnel?
And if we do, shouldn't we be looking at options that don't replicate an existing roadway, eg a tunnel from the Toowong roundabout to the Freeway at Greenslopes?
But let's not try to keep outsmarting ourselves with the actual figures. My basic premise is that those figures for a city the size of Brisbane seemed inordinately high, they appear to be salesman's figures